1 USING: kernel math sequences namespaces
2 math.miller-rabin combinators.lib
3 math.functions accessors random ;
4 IN: random.blum-blum-shub
6 ! TODO: take (log log M) bits instead of 1 bit
7 ! Blum Blum Shub, M = pq
8 TUPLE: blum-blum-shub x n ;
10 C: <blum-blum-shub> blum-blum-shub
12 : generate-bbs-primes ( numbits -- p q )
13 #! two primes congruent to 3 (mod 4)
14 [ [ random-prime ] curry [ 4 mod 3 = ] generate ] dup bi ;
17 : <blum-blum-shub> ( numbits -- blum-blum-shub )
18 #! returns a Blum-Blum-Shub tuple
20 [ find-relative-prime ] keep
21 blum-blum-shub construct-boa ;
23 ! 256 make-bbs blum-blum-shub set-global
25 : next-bbs-bit ( bbs -- bit )
26 #! x = x^2 mod n, return low bit of calculated x
27 [ [ x>> 2 ] [ n>> ] bi ^mod ]
28 [ [ >>x ] keep x>> 1 bitand ] bi ;
32 ! ! #! Cryptographically secure random number using Blum-Blum-Shub 256
33 ! [ log2 1+ random-bits ] keep dupd >= [ -1 shift ] when ;
35 M: blum-blum-shub random-32* ( bbs -- r )